Possible opiate action in the anxiolytic and antinociceptive actions of alprazolam

Chronic treatment with alprazolam reversed the effect of acute stress on the concentration of immunoreactive beta-endorphin (IR-BE) in the anterior pituitary (AP) and increased the amount of beta-endorphin (BE) relative to beta-lipotropin (B-LPH). In chronically stressed animals, administration of alprazolam did not alter the effect of a single stressful episode on the concentration of IR-BE in the AP, the NIL or the plasma, however, the amount of BE relative to B-LPH was increased in the AP and the plasma. Administration of alprazolam resulted in a significant decrease in the perception of pain. A low dose of alprazolam produced the most consistent decrease in nociception over time. The present findings suggest that alprazolam may modify the effects of acute and chronic stress on BE release from the pituitary. Moreover, alprazolam appears to have an antinociceptive effect in addition to its affect as an anxiolytic.